In rolling lines for strip and sheet, it is known to provide winding/unwinding units, possibly associated with a heating furnace, the function of which is to wind a semi-worked product, for example a slab, exiting from a working step, and then to unwind it to feed it to a subsequent process.
U.S. Pat. No. 5,335,713 describes for example a winding/unwinding device disposed at exit from a continuous casting. The device comprises two reeling stations disposed inside a furnace, which alternately exchange positions so as to be disposed selectively in a first position for winding a slab exiting from the continuous casting, and a second position to feed the slab to a rolling train. The reeling stations each comprise a rotary mandrel on which the slab winds/unwinds.
The device does not provide a passage system which can exclude its functioning in the event that it is desired to make the slab pass without proceeding to winding/unwinding. Moreover, the device does not provide auxiliary means that intervene to facilitate the unwinding of the reel when unwinding is started, thus limiting the use of this solution to determinate thicknesses.
Another disadvantage of the device is that at least one end of the reel is blocked outside the heating furnace, so that it is subjected to an unwanted lowering of the temperature.
The purpose of the invention is to solve the above problems, achieving a device which, functioning in semi-endless mode, allows to selectively wind a complete slab exiting from a roughing train and then unwind it so as to feed it to a finishing train, but which can easily and quickly be configured to function in endless mode, with the continuous passage of the roughed slab from the roughing train to the finishing train.
Another purpose of the invention is to reduce the cycle times required to complete the operations to wind a reel onto a first drum, to unwind the reel from a second drum and to reposition the drums in order to start a new winding cycle of a new reel.
The Applicant has devised, tested and embodied the present invention to overcome these shortcomings of the state of the art and to obtain these and other advantages as shown hereafter.